Using the bootstrap to establish statistical significance for relative validity comparisons among patient-reported outcome measures

Table 1 ANOVA-based F-statistic and relative validity for CKD-specific and generic PRO measures across clinically-defined groups (N = 453)

PRO measure	Dialysis			Pre-dialysis stage 3-5			Transplant			r^b(total)	F-statistic	RV	95% CI ^c
	(n = 206)			(n = 113)			(n = 134)
	Mean	(SD)	r ^a	Mean	(SD)	r ^a	Mean	(SD)	r ^a
CKD-specific
QDIS-CKD
CAT-5	39.83	(22.17)	1	16.19	(21.51)	1	19.25	(21.63)	1	1	57.43^**	1	-
Static-6	39.18	(22.86)	0.91	16.86	(21.84)	0.96	19.60	(21.29)	0.93	0.94	50.15^**	0.87	(0.72-1.03)
Static-34	35.93	(21.23)	0.93	14.90	(20.05)	0.96	18.71	(20.52)	0.95	0.95	48.01^**	0.84	(0.71-0.97)
KDQOL
Burden	48.83	(26.81)	-0.60	76.62	(24.76)	-0.73	68.21	(28.90)	-0.77	-0.74	44.46^**	0.77	(0.53-1.09)
Symptoms	71.95	(16.23)	-0.57	80.58	(15.80)	-0.65	80.03	(15.96)	-0.66	-0.65	15.11^**	0.26	(0.13-0.44)
Effects	63.41	(21.92)	-0.54	84.38	(17.59)	-0.79	77.86	(20.18)	-0.73	-0.71	43.95^**	0.77	(0.52-1.10)
Generic
SF-12
PF	37.06	(10.75)	-0.52	45.38	(11.12)	-0.57	44.88	(10.69)	-0.65	-0.63	31.12^**	0.54	(0.32-0.85)
RP	38.00	(9.41)	-0.65	45.12	(9.78)	-0.61	45.83	(9.91)	-0.63	-0.69	34.12^**	0.59	(0.38-0.89)
BP	43.19	(11.67)	-0.47	46.71	(11.27)	-0.53	47.10	(11.66)	-0.49	-0.50	5.84^**	0.10	(0.02-0.22)
GH	39.08	(11.19)	-0.47	41.99	(10.11)	-0.51	43.71	(10.93)	-0.56	-0.52	7.79^**	0.14	(0.04-0.28)
VT	45.72	(9.25)	-0.44	46.40	(10.15)	-0.46	48.35	(9.93)	-0.48	-0.44	3.04^*	0.05	(0.00-0.15)
SF	42.75	(11.79)	-0.65	47.81	(11.25)	-0.61	47.83	(10.78)	-0.60	-0.64	11.02^**	0.19	(0.07-0.34)
RE	44.59	(11.64)	-0.52	48.39	(10.05)	-0.49	48.39	(9.76)	-0.42	-0.51	7.01^**	0.12	(0.03-0.25)
PCS	36.60	(10.29)	-0.54	43.49	(10.37)	-0.56	44.08	(10.72)	-0.66	-0.64	26.61^**	0.46	(0.27-0.74)
MCS^d	49.74	(10.38)	-0.49	50.42	(9.57)	-0.45	50.55	(9.94)	-0.32	-0.40	0.32	-	-
MH^d	49.85	(10.39)	-0.43	50.71	(10.25)	-0.49	50.31	(9.95)	-0.33	-0.38	0.26	-	-

^*Significant at the 0.05 level ^** Significant at the 0.01 level.
Abbreviations: ANOVA analysis of variance, RV relative validity, CKD chronic kidney disease, PRO patient-reported outcome, QDIS-CKD quality-of-life disease impact scale for chronic kidney disease, KDQOL kidney disease quality-of-life, SF-12 Short Form 12, PF physical functioning, RP role physical, BP bodily pain, GH general health, VT vitality, SF social functioning, RE role emotional, PCS physical component summary, MCS mental component summary, MH mental health.
^a r refers to the correlation of scores between each comparison measure and the reference measure (QDIS-CKD CAT-5) within each clinical group.
^b r(total) refers to the correlation of scores between each comparison measure and the reference measure (QDIS-CKD CAT-5) for the total group (N = 453).
^c The 95% confidence interval of the RV was derived from the original data using the bootstrap BCa interval.
^d The F-statistics for SF-12 MCS and MH are small and non-significant ( p-values of 0.73 and 0.77 separately), therefore their RVs were not computed and excluded from significance test.

ISSN: 1477-7525